1. Field of the Invention
This invention relates to flash photography, and more particularly to a device for indicating the propriety of an exposure when using an electronic flash capable of automatic control of the quantity of light therefrom (hereinafter such an electronic flash will be referred to as an automatic control electronic flash).
2. Description of the Prior Art
When an object is to be flash-photographed by the use of an automatic control electronic flash, the relationship between the sensitivity of a photographic film and an aperture value of a photographic lens to give a proper exposure, is subject to restriction within a certain range because the maximum amount of flash light that can be obtained from the automatic control electronic flash is finite. In other words, under a certain definite film sensitivity, the aperture value of the photographic lens is limited to a certain range to be determined by both maximum and minimum amounts of flash light from the automatic control electronic flash. Likewise, the film sensitivity is restricted to a certain range, when the aperture value of the photographic lens is fixed. As the consequence, it is conceivable that when flash photography is conducted with either the film sensitivity or aperture value of the photographic lens maintained in its definite operable range, no appropriate exposure can be obtained.